RE: Patterning question
You also want to look for holes.
I have seen dense centers and areas that would lit ducks fly thru with out being hit.
I look for a patteren that covers the whole 30" cir.whit out spuper dense areas or holes.
This will alos tell you if your gun shoots where you think it should.
It may be the barrel , the choke tube or you.
A gun that shoots off center is a big problem.
A gun smith can bend a barrel a little to get the patteren centered for you .
Don't blame the gun right away ,2 different shooters may have different POI.
Johnch